AU734103B2

AU734103B2 - Plastic safety valve for containers

Info

Publication number: AU734103B2
Application number: AU94172/98A
Authority: AU
Inventors: Udo Schutz
Original assignee: Protechna SA
Current assignee: Protechna SA
Priority date: 1997-12-12
Filing date: 1998-11-27
Publication date: 2001-06-07
Anticipated expiration: 2018-11-27
Also published as: NO985692L; RU2150418C1; CN1221697A; PL193766B1; DE59804649D1; DK0922649T3; ES2175598T3; CA2255378A1; PL330137A1; US6058966A; DE19755205C1; JP3485814B2; EP0922649B1; AU9417298A; CA2255378C; MY117154A; NO985692D0; AR008350A1; JPH11342969A; CN1070808C

Description

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: *0 0 S S 0S 0e

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0 Name of Applicant: Protechna S.A.

Actual Inventor(s): Udo Schutz Address for Service: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: PLASTIC SAFETY VALVE FOR CONTAINERS Our Ref 559841 POF Code: 20412/106282 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): SPECIF I CAT ION PLASTIC SAFETY VALVE FOR CONTAINERS The invention pertains to a plastic safety valve for containers, especially pallet containers with an internal container of plastic and an external .jacket of metal for the transport and storage of liquids, the valve being designed as an automatic aerating and venting valve, which is integrated into a.|id or plug for sealing the filling and/or emptying opening or the aerating

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'4h/or venting opening of a container.

*o DE 2,501,228 Al describes a sealing cap, intended for containers for liquid, which can be screwed onto the neck of a bung. A safety valve of the .~aneral type in question here is integrated into this cap to serve as an trating and venting valve, which responds to positive and negative pressures in the container. A valve disk of elastic material is used in this safety ,v,4ve; when the disk is first installed, it is put under a significant amount of pretension and thus assumes the form of a segment of a sphere. When this t..'t*pe of valve is used, there is the danger that fatigue phenomena affecting the valve disk material will cause leaks to form after prolonged periods of service.

The invention is based on the task of developing a safety valve of the general type in question which meets the highest safety requirements.

This task is accomplished in accordance with the invention by a safety valve with the features of Claim 1.

The subclaims contain advantageous further elaborations of the invention.

The safety valve according to the invention is characterized by the highest functional reliability and satisfies the safety guidelines described above. In the case of pallet containers, it is the flexible internal plastic container which is equipped with the safety valve. Containers of this type have a nominal content of, for example, 1,250 liters, and a positive pressure, which can be regulated by the venting unit of the safety valve, can build up inside them; this pressure stabilizes the internal container and prevents the ,,internal container from "breathing" during transport. Breathing is associated with forcible contact between the container walls and the external metal grid 000 jcket or external sheet-metal jacket of the pallet container, which means 1at, by preventing breathing, it is also possible to prevent the internal 0:00 oooo .Iantainer from developing leaks during transport.

The invention is explained below on the basis of drawings, which illustate the following: •00 Figure 1 shows a longitudinal cross section of a safety valve, designed as an aerating and venting valve, on an enlarged scale; and Figure 2 shows a top view onto the valve of Figure 1 without its seal- Sing cap.

Safety valve 1 according to Figures 1 and 2 for tanks, barrels, pallet containers, and similar containers for the transport and storage of liquids is made of plastic and consists of an aerating unit 2 and a venting unit 3, which are integrated into a valve housing 4, which is itself designed as a threaded plug.

Valve housing 4 is screwed into a threaded plastic lid 5 used to seal the filling opening of the internal plastic container of a pallet container. The 1ft housing is sealed in threaded lid 5 by a sealing ring 6. The housing has a central hub 7, supported by ribs 8, which extend out from hub 7 in a star-like manner to a ring-shaped shoulder 9. Air holes 10 are formed between support ribs 8.

An elastic valve membrane 11 of aerating unit 2 for opening and closing air holes 10 is made out of a flexible material resistant to aggressive fluids such as plastic or rubber with appropriate additives. This membrane is designed with the profile of a hat 12 and has a central, reinforced mounting hub 13. With opening 14 of the hat pointing toward ring-shaped shoulder 9 of .valve housing 4, valve membrane 11 is pushed onto hub 7 of the valve housing g; :far as a shoulder 15 on the housing.

Valve membrane 11 is held on the hub by a surge cover 17, which is ,,pr-ssed onto inner end 16 of hub 7. A clamping sleeve 18 with axial clamping webs 19 is molded onto curved surge cover 17; these webs press valve membrane .1 i by its mounting hub 13 against shoulder 15 of hub 7 of valve housing 4 in *..*sich a way that, when aerating unit 2 is in its closed position, valve membrane 11 rests by a ring-shaped edge 20 under pretension against the inside Srface 21 of ring-shaped shoulder 9 of valve housing 4, which forms a valve 0 seat. Valve membrane 11 is also supported by a ring-shaped web 23 molded onto 4S@ inside edge 22 of ring-shaped' shoulder 9. Flow channels 28 for the air or gas escaping under pressure from a container through venting unit 3 are provided between clamping sleeve 18 of surge cover 17 and hub 7 of valve housing 4, these channels being connected to each other by through-slots 24 in inner end of clamping sleeve 18 and through-slots 26 in inner end 16 of hub 7 of valve housing 4.

Support ribs 8 of hub 7 have a profile 29 which conforms to hat-shaped profile 12 of valve membrane 11 so that they can effectively support the valve membrane against positive pressure in the container.

Outer edge 30 of surge cover 17 cooperates with inner end 31 of valve housing 4 to form a peripheral slot 32 for the air entering a container when aerating unit 2 is open and for the air or gas escaping from a container when venting unit 3 is open.

Between valve membrane 11 and surge cover 17, a surge disk 33 with a hatshaped profile 34, coaxial to the membrane and the lid, is provided; this pro- ,,file has a central opening 35 for air or gas. Surge disk 33 cooperates with surge cover 17 to form a labyrinth, which protects valve membrane 11 against

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surges of liquid entering safety valve 1.

The curved surface of surge cover 17 facing valve membrane 11, further- 0e*O Si-re, forms a run-off surface 38 for the surging liquid which has entered safety valve 1.

Axial clamping tabs 40 are molded onto outside surface 39 of surge cover Distributed uniformly around the periphery of the cover, they press surge disk 33 against a shoulder 41 on inside surface 42 of valve housing 4.

Venting unit 3, inserted into the outer end 43 of through-hole 44 in hub 7 of valve housing 4, is equipped with a valve plate 45 of elastic material.

bottom surface of this plate rests on inward-beveled, outer edge 46 of hub 7, which forms a valve seat. A mounting pin 47 with a head 48 is molded onto valve plate 45 to form a single unit with it; this pin locks behind an undercut 49 in through-hole 44 of hub 7 to fasten valve plate 45, which rests under slight pretension on outer edge 46 of hub 7. On the periphery of mounting pin 47 and head 48, continuous axial air or gas through-channels 50, 51 are provided.

A grid 53 of plastic is welded to external surface 52 of ring-shaped shoulder 9 of valve housing 4. This grid covers air holes 10 between support ribs 8 of hub 7 as protection against the intrusion of insects.

On outer edge 54 of valve housing 4, adjacent to ring-shaped shoulder 9, hook-shaped retaining teeth 55 are provided to engage with a sealing cap 56, which can thus be clamped firmly to the housing. Openings 57 for the air flowing into a container when aerating unit 2 of safety valve 1 is open and for the air or gas flowing out of a container when venting unit 3 is open are prQvided between retaining teeth 55 and sealing cap 56, which projects out- :%ward beyond the teeth. On inside surface 58 of sealing cap 56, a certain

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;*tial distance away from its outer edge 59, a ring-shaped web 60 with an "i aercut 61 is formed; when sealing cap 56 is pressed down onto valve housing 0#00 .,:this undercut interlocks with retaining teeth 55 of the housing.

Four molded segments 62 on outside surface 52 of ring-shaped shoulder 9 "wtkve to accept a spider wrench for screwing safety valve 1 into and out of 000g readed lid When negative pressure, for example, develops in the internal plastic cantainer of a pallet container equipped with safety valve 1 as liquid is 5 being removed, valve membrane 11 of aerating unit 2 opens, so that air can 5o• flow into continuous air openings 55, 10, 35, 32 of safety valve 1 in the direction of arrow a shown in Figure 1.

The-stiffness of valve plate 45 of venting unit 3 of safety valve 1 is to be calculated in such a way that a positive pressure of, for example, mbars, can build up in the internal container of the pallet container and thus stabilize the container. When the positive pressure in the container exceeds the cited limit, valve plate 45 of venting unit 3 of safety valve 1 opens, so that the air or gas which is under positive pressure can escape from the container in the direction of arrow b through air openings and flow channels 32, 35, 24, 28, 26, 44, 51, 50, 10, and 57 of safety valve 1.

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Claims

2. Safety valve according to Claim 1, characterized in that the support ribs of the hub have a profile conforming to the hat-shaped profile (12) of the valve membrane (11) so that they can effectively support the valve membrane (11) when there is positive pressure in the container, and in that the valve membrane (11) is also supported by a ring-shaped web (23) molded onto the inner edge (22) of the ring-shaped shoulder of the valve housing
3. Safety valve according to Claim 1 or Claim 2, characterized in that the valve membrane which is made out of a flexible material resistant to aggressive liquids, a material such as plastic or rubber-with appropri- ate additives, has a central, reinforced mounting hub (13).
4. Safety valve according to one of Claims 1-3, characterized in that a clamping sleeve (18) with axial clamping webs (19) is molded onto the curved surge cover (17) to press the mounting hub (13) of the valve membrane (11) against the shoulder (15) of the hub of the valve housing and in 0* :.that, between the clamping sleeve (18) of the surge cover (17) and the hub (7) 4** Qfthe valve housing flow channels (28) for the pressurized air and/or as escaping from the container through the venting unit are provided, ,,h3ch are connected to each other via through-slits (24) in the inner end of the clamping sleeve (18) of the surge cover (17) and through-slits (26) in *.tIre inner end (16) of the hub of the valve housing O. 5. Safety valve according to one of Claims 1-4, characterized in that e curved surface of the surge cover (17) facing the valve membrane (11) 4 a run-off surface (38) for surges of liquid which have entered the safety valve
6. Safety valve according to one of Claims 1-5, characterized in that the surge disk (33) has a hat-shaped profile (34) with a central opening for air or gas.
7. Safety valve according to one of Claims 1-6, characterized by axial clamping tabs which are molded onto the outside surface (39) of the surge cover (17) and distributed around the periphery of the cover, these tabs pressing the surge disk (33) against a shoulder (41) on the inside surface (42) of the valve housing
8. Safety valve according to one of Claims 1-7, characterized in that the surge disk (33) is installed in the valve housing with the opening of its hat-shaped profile (36) facing the valve membrane (11) and thus forms a run-off surface (37) for surges of liquid entering the valve
9. Safety valve according o one of Claims 1-8, characterized by the automatic control of positive pressure in the container by the venting unit Safety valve according to Claim 9, characterized by the control of the positive pressure in the container by the venting unit to 50-120 mbrs, preferably 80 mbars.
11. Safety valve according to one of Claims 1-10, characterized in that .A'mounting pin (47) with a head (48) is formed integrally on the valve plate of the venting unit which pin locks behind an undercut (49) of the .1*iough-hole (44) of the hub to fasten the valve plate which rests *,ttder slight pretension against the outer edge (46) of the hub of the valve housing axial air or gas channels (50, 51), which merge into each being provided on the periphery of the mounting pin (47). S
12. Safety valve according to one of Claims 1-11, characterized by a 9. S..ggid preferably of plastic, attached to the outside surface (52) of the ring-shaped shoulder of the valve housing which grid covers the air openings (10) between the support ribs and the hub as protection against the intrusion of insects.
13. Safety valve according to Claim 12, characterized in that the grid (53) is welded to the outside surface (52) of the ring-shaped shoulder
14. Safety valve according to one of Claims 1-13, characterized by hook- shaped retaining teeth (55) formed on the outer edge (54) of the valve housing for clamping the sealing cap on the inside surface (58) of which, a certain radial distance away from the outer edge a ring-shaped web with an undercut (61) is formed, which, when the sealing cap (56) is clamped down onto the valve housing interlocks with the retaining teeth (55) of the housing. DATED: 26th November, 1998 PHILLIPS ORMONDE FITZPATRICK Attorneys for: *gOTECHNA S.A. 0. 0 0 ~Dd~bdgdc .1 0 0 *000 0 a a 0